1. Field of the Disclosure
The present disclosure relates to a capacitive-type input device in which first electrode layers and second electrode layers are placed on a translucent substrate so as to be insulated from each other and to a method of manufacturing the input device.
2. Description of the Related Art
In various types of information processing apparatuses, a translucent input device is placed in front of a color liquid crystal display panel. This type of input device, called a touch panel, has capacitances among electrodes so that when a finger of a person approaches the touch panel, the access position of the finger can be determined on coordinates from a change in movement of electric charges due to the approach of the finger.
One type of input device is structured so that X electrodes are formed on one of two translucent substrates and Y electrodes are formed on the other, after which the two translucent substrates are overlaid so as to form a capacitance between each X electrode and its corresponding Y electrode. In this structure, however, since two translucent substrates are needed, the number of parts is increased. Furthermore, since processes to, for example, mutually align the two translucent substrates, laminate them, and mutually bond them and are needed, man-hours are increased. This leads to the problem that the manufacturing costs are increased.
Recently, input devices are emerging in which many electrodes are formed on one surface of a single translucent substrate so as to form capacitances among the electrodes. Since, in this method, the structure has only one translucent substrate, the number of parts is small and the number of manufacturing man-hours can be reduced. However, many electrodes need to be formed on one surface of the translucent substrate and many wiring layers that individually extend from their relevant electrode layers need to be formed. Therefore, the width dimension of each wiring layer needs to be small, leading to the drawback that wire resistances become large. In particular, if a large input device is structured, an individual wire becomes long, so the wire resistances become further large. A possible solution to this is to increase the width dimension of each wiring layer. If the width of the wiring layer is increased, however, the wiring density of electrode layers needs to be lowered and the resolution of detection is thereby lowered. If, for example, a so-called multi-touch method, in which a manipulation made by a plurality of fingers is detected, is used, detection precision is lowered.
An invention related to a capacitive-type touch panel that uses a single transparent substrate is described in Japanese Unexamined Patent Application Publication No. 2011-76386.
With this touch-panel, first electrode layers are formed on a transparent substrate and the first electrode layers are covered with a transparent insulating layer. Second electrode layers are formed on the surface of the insulating layer so that capacitances are formed between the first electrode layers and the second electrode layers.
With the touch panel described in Japanese Unexamined Patent Application Publication No. 2011-76386, since the first electrode layers and second electrode layers are formed on one surface of a transparent substrate, the number of substrates can be reduced and costs can thereby be reduced. With this touch panel, however, both the first electrode layer and second electrode layer are formed from an ITO film. As for an electrode layer formed from an ITO film, it is necessary to form an ITO film on an electrode forming surface in a sputtering process and further to form an electrode pattern in a wet etching process. If, however, both the first electrode layer and second electrode layer are formed in the sputtering process and etching process, the number of manufacturing processes is increased and it is difficult to reduce the manufacturing costs.
In addition, what is the insulating layer positioned between the first electrode layers and the second electrode layers is like is not described in Japanese Unexamined Patent Application Publication No. 2011-763861. To sputter an ITO layer on the insulating layer, however, it is necessary to form the insulating layer from an inorganic oxide or the like in a sputtering process or the like. If all of the first electrode layers and second electrode layers need to be formed in a sputtering process, the manufacturing processes become further complex and the manufacturing costs become high. In addition, if the insulating layer is formed from an inorganic oxide, the flexibility of the touch panel is lowered. Even if, for example, the substrate is formed from a resin film, it becomes difficult to, for example, flexibly deform the touch panel.